1965-1966 Mustang Rear Framerail and Trunk Floor Replacement

10 Visible in this photo after we turned the framerail over (as if you were looking up under the car), is a strange patch someone made. By forming a steel support around the rusted framerail, and then using carriage bolts to retain the support to the trunk floor, the patch somehow worked, but considering the time involved spent completing it, a new rail could have been installed. You can see the heads of these bolts in photo 5.

11 Since we also were installing a new trunk-floor assembly, the remaining trunk-floor metal had to be removed. To find the original spot welds, all old seam sealer must be scraped away first.

12 Using nothing more fancy than a wire wheel in an electric drill, Gaydos cleans away old paint and rust, in search of the original spot welds.

13 Don't forget that there are spot welds for the trunk floor within the inner wheelhouse. Gaydos uses his wire wheel in this area, too.

14 Once all the original spot welds have been located, Gaydos drills out the spot welds. Some are completely drilled through, if the metal on both sides is being replaced. He carefully drills through only the top layer of other areas.

15 Gaydos then continues by separating the trunk corner reinforcement which will be reused and cutting along the trunk floor on each side of the framerail.

16 Again with the hammer and chisel, Gaydos separates the old trunk floor from the remaining good section of framerail. This will allow Gaydos the luxury of installing the framerail by inserting a step of one rail inside the other for added strength.

17 The length of the removed framerail section is measured to determine the overall length of the new framerail section. In this case, we have removed 18 inches of framerail from the trunk reinforcement forward.

18 The new rail is measured out to the new length of 18 inches and a scribe mark is made at that point.

19 Gaydos then adds 3 inches to the original measurement. These additional inches will be used to make a step or flange, if you will to allow the new rail to be inserted within the old rail for strength. The remaining new framerail is removed.

20 After the old section of framerail has been cleaned and a coating of 3M Weld-Thru coating applied, the shortened and modified framerail is tapped into place and the length verified.

21 Gaydos begins the final welding of the new framerail on the inside, working his MIG welder tip around all the edges of the step for a complete and continuous weld.